Java 获取当天的零点时间戳

/**
     * 获取当天的零点时间戳
     *
     * @return 当天的零点时间戳
     */
    public static long getTodayStartTime() {
   		//设置时区
        Calendar calendar = Calendar.getInstance(TimeZone.getTimeZone("GMT+8")); 
        calendar.set(Calendar.HOUR_OF_DAY, 0);
        calendar.set(Calendar.MINUTE, 0);
        calendar.set(Calendar.SECOND, 0);
        return calendar.getTimeInMillis();
    }